1. Field of the Invention
The present invention relates to tools for driving fasteners such as screws, and more particularly, to an illuminating screwdriver having an LED situated in a bore extending through the shaft.
2. Description of Prior Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
Tools for driving fasteners such as screws are common. Conventional tools of this type include a solid handle, made of plastic, rubber, or wood, from which a rigid metal shaft extends. The screw-engaging end of the shaft is shaped to engage a correspondingly shaped recess in the screw head. For conventional screw heads, the shaft end is tapered to form a blade.
Screwdrivers sometimes must be used to drive screws in poorly lighted places. In such instances, a light source may be required to provide sufficient light to enable the user of the screwdriver to correctly align the screw-engaging end of the screwdriver with the recess in the screw head. A flashlight or other portable light source could be used if space permits. However, such light sources must be held by the user while using the screwdriver, forcing the user to manipulate the screwdriver and the screw with one hand, while holding the light source with the other. Manipulating the screwdriver and the screw with one hand is difficult.
In order to overcome this problem, screwdriver handles have been fashioned to include a battery and a standard incandescent flashlight-type bulb which shines light from the front of the handle along the exterior of the shaft, toward the screw-engaging end of the shaft. See, for example, Singleton, U.S. Pat. No. 4,107,765; Nalbandian U.S. Pat. No. 4,283,757; McKain U.S. Pat. No. 5,369,555; Berg, U.S. Pat. No. 4,936,171 and Barlet et al. U.S. Pat. No. 2,670,427.
However, the devices disclosed in the above mentioned patents have a disadvantage inherent in having such a bulb located in the handle, and thus far from the screw-engaging end of the shaft, which is the point where illumination is required. Because the light from the bulb spreads out as it travels along the shaft, and because of the limitations on the light output of a standard battery operated incandescent bulb, placing the bulb in the handle has proven to be less than adequate for illuminating the area immediately in front of the blade of the screw-engaging end of the shaft.
U.S. Pat. No. 1,603,985 to Rosenberg unsuccessfully attempted to overcome that problem by placing the bulb within a bore in the shaft. That arrangement required a very small bulb which provided inadequate light and, at the same time, required such a large bore to accommodate the bulb that the strength of the shaft is weakened substantially.
Another attempt to overcome the problem inherent in the above mentioned patents is disclosed by Jong-Pyng Jeng, in U.S. Pat. Nos. 5,124,893 and 5,211,468. Those patents teach a device in which bulbs are mounted in a member which slides along the shaft. That configuration allowed the bulbs to be situated close to the screw-engaging end of the shaft. However, the bulb-carrying member resulted in an extremely cumbersome tool in which the view of the screw-engaging end of the shaft is at least partially obstructed when the bulb-carrying member is situated close enough to the blade to provide adequate illumination Further, the device required exposed wires extending from the bulb-carrying member to the handle where the battery is located.
In my U.S. Pat. No. 5,826,969, a screwdriver is disclosed in which the handle has a cavity for retaining a battery and a standard incandescent bulb. The shaft, extending from one end of the handle, is provided with a bore or channel extending from the handle and through the screw-engaging end of the shaft. The blade at the end of the shaft is bifurcated, having blade sections one either side of the bore opening. The bore guided light from the bulb down the shaft and out the end of the shaft, to illuminate the area proximate the front of the blade.
That invention overcame the disadvantages of the above noted prior art structures by utilizing a light guiding bore extending within the interior of the shaft and a bifurcated blade at the screw-engaging end of the shaft. The bore directs the light down the shaft and through the bifurcated blade to illuminate the area proximate the front of the screw-engaging end of the shaft. However, the structure of U.S. Pat. No. 5,826,969 still does not provide an optimum result.
It has been suggested, for example in U.S. Pat. No. 4,302,797 to Cooper, that a fiber optic bundle be used in the bore of the shaft to convey light from bulb in the handle to the screw-engaging end of the shaft. However, even that approach has proven inadequate.
The present invention constitutes a further improvement over my patented device, and that proposed by Cooper. It utilizes a LED instead of an incandescent bulb as the light source. Further, the LED is situated within the bore of the shaft, at a location proximate the end of the screw-engaging end of the shaft, instead of in a remote position in the handle.
Since the LED is situated close to the end of the shaft, the light from the LED does not spread out to any significant extent and almost all of the light is focused on the point where illumination is required. Thus, the relatively high intensity light from the LED provides ample illumination, exactly where it is needed to illuminate the area in front of the screw-engaging end of the shaft.
Further, because the diameter of the LED is quite small, the inner diameter of the bore can be small relative to the outer diameter of the shaft. Hence, the bore does not significantly reduce the strength of the shaft.
The LED is connected to the battery power source in the handle by wires that extend through the bore, from the handle to the LED. A spring-loaded pushbutton switch is situated on the exterior of the handle to actuate the LED when depressed.
It is therefore, a prime object of the present invention to provide a LED illuminated screwdriver.
It is another object of the present invention to provide a LED illuminated screwdriver in which adequate illumination of the area in front of the screw-engaging end of the shaft is provided by mounting the LED close to the end of the shaft.
It is another object of the present invention to provide a LED illuminated screwdriver in which the LED is mounted within a bore extending though the shaft.
It is another object of the present invention to provide a LED illuminated screwdriver in which the strength of the shaft is not weakened substantially by the bore in which the LED is situated.
It is another object of the present invention to provide a LED illuminated screwdriver in which the inner diameter of the bore is relatively small as compared to the outer diameter of the shaft.
It is another object of the present invention to provide an LED illuminated screwdriver with interchangeable heads for use with multiple screw heads having various configurations.